CN110893513A - Laser processing system and laser processing method - Google Patents

Abstract

The invention provides a laser processing system and a laser processing method. The laser processing system can effectively utilize the auxiliary gas emitted from the nozzle, and can effectively blow away the workpiece material melted by the laser beam. The laser processing system comprises: a nozzle having an emission port for emitting a jet of assist gas along an optical axis of a laser beam, and forming a maximum point of a velocity of the jet at a position distant from the emission port, the laser processing system comprising: in the process of processing a workpiece by a laser beam, a nozzle is arranged at a target position determined according to the position of a maximum point with respect to a processing position of the workpiece (W).

Description

Laser processing system and laser processing method

Technical Field

The present invention relates to a laser processing system and a laser processing method.

Background

A laser processing system having a nozzle that emits an assist gas for blowing away a workpiece material melted by a laser beam when the workpiece is processed by the laser beam is known (for example, japanese patent application laid-open No. 2017-051965).

Conventionally, there has been a demand for a laser processing system capable of effectively blowing away a workpiece material melted by a laser beam by effectively using an assist gas emitted from a nozzle.

Disclosure of Invention

In one aspect of the present disclosure, a laser processing system includes: a nozzle having an emission port for emitting a jet of assist gas along an optical axis of a laser beam, and forming a maximum point of a velocity of the jet at a position distant from the emission port, the laser processing system comprising: in the process of processing a workpiece by a laser beam, the nozzle is arranged at a target position determined from the position of the maximum point with respect to a processing portion of the workpiece.

In another aspect of the present disclosure, in a method of laser-processing a workpiece using the above-described laser processing system, a jet flow is emitted from an emission port of a nozzle in a state where the nozzle is disposed at a target position, and the workpiece is processed by a laser beam.

Since the assist gas emitted from the nozzle during processing of the workpiece can be blown onto the workpiece at a velocity higher than the velocity of the region near the emission port of the nozzle, the assist gas can be effectively used, and the workpiece material melted by the laser beam can be effectively blown away.

Drawings

Fig. 1 is a diagram of a laser processing system.

Fig. 2 is an image obtained by imaging the jet of the assist gas emitted from the nozzle by a high-speed camera.

Fig. 3 is a diagram for explaining the maximum point of the velocity of the jet, the upper diagram schematically shows the relationship between the velocity of the jet and the position x from the emission hole, and the lower diagram shows the image of fig. 2.

Fig. 4 is a view of the jet flow observation device.

Fig. 5 is a block diagram of the jet flow observation device shown in fig. 4.

Fig. 6 is a diagram of another jet flow observing apparatus.

Fig. 7 is a block diagram of the jet flow observation device shown in fig. 6.

Fig. 8 is a diagram of another jet observation device.

Fig. 9 is a block diagram of the jet flow observation device shown in fig. 8.

Fig. 10 is a diagram of another laser processing system.

Fig. 11 is a block diagram of the laser processing system shown in fig. 10.

Fig. 12 is a diagram of another alternative laser machining system.

Fig. 13 is a block diagram of the laser processing system shown in fig. 12.

Fig. 14 is a flowchart showing an example of the operation flow of the laser processing system shown in fig. 12.

Fig. 15 is a flowchart showing an example of the flow of step S14 in fig. 14.

Fig. 16 is a view schematically showing the relationship between the output data of the measuring instrument shown in fig. 12 and the distance from the emission opening.

Fig. 17 is a diagram of another alternative laser machining system.

Fig. 18 is a block diagram of the laser processing system shown in fig. 17.

Fig. 19 is a diagram of another alternative laser machining system.

Fig. 20 is a block diagram of the laser processing system shown in fig. 19.

Fig. 21 is a flowchart showing an example of the operation flow of the laser processing system shown in fig. 19.

Fig. 22 is a view of the jet flow adjustment device.

Fig. 23 shows an example of the mechanism shown in fig. 22.

Fig. 24 shows another example of the mechanism portion shown in fig. 22.

Fig. 25 is a diagram of another alternative laser machining system.

Fig. 26 is a block diagram of the laser processing system shown in fig. 25.

Fig. 27 is a flowchart showing an example of the operation flow of the laser processing system shown in fig. 25.

Fig. 28 shows an example of the measuring instrument.

Fig. 29 shows another example of the measuring device.

Detailed Description

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. In the various embodiments described below, the same elements are denoted by the same reference numerals, and redundant description is omitted. First, the laser processing system 10 will be described with reference to fig. 1.

The laser processing system 10 includes: a laser oscillator 12, a laser processing head 14, an auxiliary gas supply device 16, and a placement device 18. The laser oscillator 12 oscillates laser light inside and emits laser light to the outside. The laser oscillator 12 may be CO₂A laser oscillator, a solid-state laser (YAG laser) oscillator, a fiber laser oscillator, or any other type of laser oscillator.

The laser processing head 14 includes: a head body 20, an optical lens 22, a lens driving section 23, and a nozzle 24. The head body 20 is hollow, and the proximal end portion thereof is connected to an optical fiber 26. The laser beam emitted from the laser oscillator 12 propagates through the optical fiber 26 and enters the head body 20.

The optical lens 22 has a collimator lens, a focusing lens, and the like, and collimates and condenses the laser beam incident inside the head body 20 to irradiate the workpiece W. The optical lens 22 is housed in the head body 20 so as to be movable in the direction of the optical axis O.

The lens driving unit 23 moves each optical lens 22 in the direction of the optical axis O. The lens driving unit 23 can control the position of the focal point of the laser beam emitted from the nozzle 24 in the optical axis O direction by adjusting the position of the optical lens 22 in the optical axis O direction.

The nozzle 24 is hollow and is provided at a distal end portion of the head body 20. The nozzle 24 has a conical outer shape in which the cross-sectional area perpendicular to the optical axis O decreases from the base end portion toward the tip end portion thereof, and has a circular injection port 28 at the tip end portion thereof. A hollow cavity 29 is formed inside the nozzle 24 and the head body 20. The laser beam propagating through the optical lens 22 is emitted from the emission port 28.

The auxiliary gas supply device 16 supplies an auxiliary gas to a chamber 29 formed inside the nozzle 24 and the head body 20 via a gas supply pipe 30. The auxiliary gas is, for example, nitrogen or air. The assist gas supplied to the chamber 29 is emitted as a jet stream from the emission port 28 along the optical axis O of the laser beam together with the laser beam. Nozzle 24 creates a maximum in jet velocity at a location remote from exit 28.

Next, the jet of the assist gas emitted from the nozzle 24 will be described with reference to fig. 2 and 3. Fig. 2 is an image obtained by imaging the jet flow emitted from the emission port 28 of the nozzle 24 with a high-speed camera. Fig. 3 schematically shows the image of the jet flow shown in fig. 2 and a relationship between the velocity V of the jet flow and the position x along the optical axis O in the direction away from the injection hole 28.

In the present application, the "velocity" of the jet is defined as: including the flow rate (unit: m/sec) and flow rate (unit: m) of the assist gas³Sec). The jet flows shown in fig. 2 and 3 are formed under conditions in which the supply pressure to the chamber 29 is 1MPa and the opening size (diameter) of the injection port 28 is 2 mm.

As shown in fig. 2 and 3, the jet of the assist gas emitted from the nozzle 24 forms a first Mach disk region 33(Mach disk region) and a second Mach disk region 35 whose velocities V are extremely large at positions distant from the emission port 28 in the direction of the optical axis O. The first mach disk region 33 contains the position x of the first maximum point 32 of the velocity V₁The second mach disk region 35 contains the position x of the second maximum point 34 of the velocity V₂。

More specifically, as shown in the graph of fig. 3, the velocity V of the jet gradually increases as the position (i.e., x is 0) of the injection port 28 is farther along the optical axis O, and at the position x, the velocity V of the jet gradually increases₁Where is the first maximum point 32. In addition, in the jet stream of the image shown in FIG. 3, x₁4 mm. At an inclusion position x₁Is formed in the first mach disk region 33: a so-called mach disk in which the jet flow and the reflected wave of the assist gas reflected at the atmospheric boundary outside the jet flow interfere with each other and are intensified.

Following from position x₁Further away from the exit opening 28 along the optical axis O, the velocity V decreases sharply and then increases again, at a position x₂Becomes the second maximum point 34. In the inclusion ofPosition x₂The second mach disk is formed in the inner second mach disk region 35.

As described above, in the jet flow emitted from the nozzle 24, the plurality of mach disks are formed in the direction of the optical axis O, and the velocity V of the jet flow has the plurality of local maximum points 32 and 34 in the direction of the optical axis O. The number of formed mach disks (i.e., maximum points) increases in accordance with the velocity V of the ejected jet.

In the present invention, when the laser processing system 10 performs laser processing on the workpiece W, the nozzle 24 is arranged at the position x corresponding to the local maximum points 32 and 34 with respect to the processing portion S of the workpiece W₁、x₂The target position is determined so as to arrange the workpiece W (specifically, the machining site S of the workpiece W) in one of the mach disk regions 33 and 35.

Conventionally, it is desirable that the pressure of the assist gas blown onto the workpiece W during laser processing of the workpiece W is as high as possible. The pressure of the assist gas is maximum at the position of the ejection port 28. Therefore, conventionally, when laser processing is performed on the workpiece W, the workpiece W is brought as close as possible to the injection port 28 having the highest pressure. Specifically, the workpiece W is conventionally disposed in the approach area 36 in fig. 3. The approach region 36 is a region in which the pressure of the assist gas is close to the maximum value, and is closer to the injection hole 28 than the first maximum point 32.

When the nozzle 24 is brought close to the workpiece W in this manner, when laser processing is performed while the nozzle 24 is moved at a high speed relative to the workpiece W, plasma is likely to be generated between the nozzle 24 and the workpiece W. When the plasma is generated, the finished surface of the workpiece W may become rough. When the nozzle 24 is brought close to the workpiece W, particles of the workpiece W scattered by melting in the laser processing enter the nozzle 24 through the injection hole 28, and the possibility of contaminating the components (e.g., cover glass) of the laser processing head 14 is increased.

The inventors intensively studied the results to obtain the following knowledge: as the velocity V of the assist gas blown onto the workpiece W during the laser processing of the workpiece W is higher, the material of the workpiece W melted by the laser beam can be blown away more effectively by the assist gas.

Based on this knowledge, the present inventors found that: when the jet flow of the assist gas is emitted from the emission port 28 of the nozzle 24, focusing on the formation of the local maximum points 32 and 34, if the workpiece W is disposed in one mach disk region 33 or 35 during laser processing of the workpiece W, the assist gas can be blown onto the workpiece W at a velocity V greater than that of the vicinity region 36 of the emission port 28.

Referring again to fig. 1, the arranging device 18 arranges the nozzle 24 at a position x corresponding to the local maximum point 32 or 34 with respect to the machining site S in order to arrange the workpiece W (for example, the machining site S) in the mach disk region 33 or 35₁Or x₂And the determined target location. Specifically, the configuration device 18 has: a workpiece table 38, a y-axis movement mechanism 40, an x-axis movement mechanism 42, and a z-axis movement mechanism 44.

The work table 38 is fixed to the floor of the working unit. For example, the workpiece table 38 has a plurality of pins extending in the z-axis direction in fig. 1, and the workpiece W is set on a setting surface formed by the tips of the plurality of pins. The z-axis direction is substantially parallel to the vertical direction, for example.

The y-axis moving mechanism 40 has a pair of rail mechanisms 46 and 48, and a pair of cylinders 50 and 52. The track mechanisms 46 and 48 extend in the y-axis direction, for example, with built-in servo motors and ball screw mechanisms (both not shown). The rail mechanisms 46 and 48 move the cylinders 50 and 52, respectively, in the y-direction.

The x-axis moving mechanism 42 is fixed to the cylinders 50 and 52, and extends between the cylinders 50 and 52, for example, by a built-in servo motor and a ball screw mechanism (both not shown). The x-axis moving mechanism 42 moves the z-axis moving mechanism 44 in the x-axis direction. The z-axis moving mechanism 44 incorporates a servo motor and a ball screw mechanism (both not shown), for example, and moves the laser processing head 14 in the z-axis direction. The laser processing head 14 is provided on the z-axis moving mechanism 44 such that the optical axis O of the emitted laser beam is parallel to the z-axis.

When the workpiece W is processed, the placement device 18 places the nozzle 24 at a target position with respect to the processing site S. For example, a control unit (not shown) provided in the laser processing system 10, which will be described later, controls the placement device 18 to automatically place the nozzle 24 and the workpiece W at the target position. Alternatively, the operator may manually operate the placement device 18 to place the nozzle 24 at the target position with respect to the machining site S.

Next, the assist gas supply device 16 supplies the assist gas to the chamber 29, and emits a jet flow of the assist gas having the mach disk regions 33 and 35 from the emission port 28. Then, the laser oscillator 12 emits a laser beam to the laser processing head 14, and the laser processing head 14 emits the laser beam from the emission port 28 to irradiate the workpiece W. At this time, the lens driving unit 23 adjusts the position of the optical lens 22 in the optical axis O direction so that the focal point of the laser beam emitted from the emission port 28 is disposed at the processing site S.

In this way, the workpiece W is laser-machined while being disposed in the mach disk region 33 or 35 of the jet flow. According to this configuration, when the workpiece W is machined, the assist gas emitted from the nozzle 24 can be blown onto the workpiece W at a velocity V higher than the approaching region 36 of the injection port 28, and therefore the assist gas can be effectively utilized to effectively blow away the material of the workpiece W melted by the laser beam.

Further, since the generation of the plasma described above can be suppressed as compared with the case where the workpiece W is disposed in the proximity region 36 of the injection port 28, the finishing quality of the workpiece W can be improved. Further, compared to the case where the workpiece W is disposed in the proximity region 36, since the scattered particles of the workpiece W generated during the laser processing can be suppressed from entering the inside of the nozzle 24, the contamination of the components of the laser processing head 14 can be suppressed.

Next, the jet flow observation device 60 will be described with reference to fig. 4 and 5. The jet flow observation device 60 acquires the position x indicating the local maximum points 32 and 34 described above₁、x₂The information of (1). The jet flow observation device 60 includes: a control section 62, a dummy 64, a measuring device 66, and the above-described placement device 18. The control unit 62 includes a processor (CPU, GPU, etc.) and a storage unit (ROM, RAM, etc.), and controls the measuring device 66 and the placement device 18.

The dummy workpiece 64 is disposed on the mounting surface of the workpiece table 38. The dummy workpiece 64 has the same outer shape (size) as the workpiece W, and has a dummy processing portion 64a corresponding to the processing portion S. In the example shown in fig. 4, the dummy workpiece 64 is disposed at a position different from the position where the workpiece W is disposed during laser processing.

The measuring instrument 66 measures the velocity V of the jet flow emitted from the emission port 28 at the position of the dummy processing portion 64a (or at a position slightly shifted from the dummy processing portion 64a in the direction of the emission port 28). For example, the measuring device 66 includes a heat-ray anemometer that measures the velocity V in contact therewith, and is disposed in the jet flow and includes a heat ray whose resistance value changes in accordance with the velocity V. Alternatively, the measuring device 66 may have a laser flowmeter for measuring the velocity V in a non-contact manner, and the laser flowmeter may include an optical sensor for measuring the velocity V by irradiating the jet with light.

The measuring instrument 66 measures the velocity V of the jet flow and outputs the measured velocity V to the control unit 62 as output data (measured value) α. the measuring instrument 66 may be disposed on the dummy workpiece 64 or may be disposed separately from the dummy workpiece 64. the dummy workpiece 64 is disposed forward (i.e., downstream) in the flow direction of the jet flow, and the measuring instrument 66 measures the velocity V at a position between the injection port 28 and the dummy workpiece 64.

The configuration device 18 has: the workpiece table 38, the y-axis moving mechanism 40, the x-axis moving mechanism 42, and the z-axis moving mechanism 44 move the laser processing head 14 in the x-axis, y-axis, and z-axis directions, thereby moving the laser processing head 14 relative to the dummy workpiece 64 and the measuring instrument 66.

Next, the position x at which the maximum points 32 and 34 are obtained using the jet flow observation device 60 is set to the position x₁、x₂The method of (1) is explained. First, the control unit 62 operates the placement device 18 to place the laser processing head 14 at the measurement initial position. When the laser processing head 14 is disposed at the measurement initial position, as shown in fig. 4, the laser processing head 14 is positioned with respect to the dummy workpiece 64 and the measuring instrument 66 so that the optical axis O of the laser processing head 14 intersects the dummy processed portion 64a of the dummy workpiece 64.

Further, the distance d between the injection hole 28 and the measurement position of the measuring instrument 66 (i.e., the position of the dummy processing portion 64 a)_aIs an initial value d_a0. As an example, the initial value d_a0The measurement position of the measuring instrument 66 is set to be the same as that of the proximity region 36 in fig. 3And the approach position of the ejection port 28.

As another example, the initial value d_a0The measurement position of the measuring device 66 is set to be arranged at the following positions: the jet flow is sufficiently far downstream from the position where the maximum point (in the example of fig. 3, the second maximum point 34) farthest from the injection hole 28 is estimated to exist. The initial value d is preset by the operator_a0。

Next, the control unit 62 sends a command to the assist gas supply device 16, and upon receiving the command, the assist gas supply device 16 supplies the assist gas to the chamber 29 at the supply pressure Ps. The nozzle 24 emits a jet of assist gas having maxima 32 and 34 of velocity V as shown in fig. 2 and 3.

Next, the controller 62 operates the placement device 18 to move the laser processing head 14 in the z-axis direction so that the distance d between the measurement position of the measuring instrument 66 and the injection hole 28_aA change occurs. For example, the initial value d is set as described above_a0When the measurement position of the measuring instrument 66 is set to be located at the position close to the injection hole 28, the control unit 62 operates the placement device 18 to move the laser processing head 14 in the positive z-axis direction so as to increase the distance d_a。

As another example, at the above-mentioned initial value d_a0When the measurement position of the measuring instrument 66 is set to be disposed downstream of the maximum point farthest from the injection hole 28, the control unit 62 operates the disposing device 18 to move the laser processing head 14 in the negative z-axis direction so as to decrease the distance d_a。

While the placement device 18 moves the laser machining head 14 in the z-axis direction, the control unit 62 sends a command to the measuring device 66 to cause the measuring device 66 to continuously measure the velocity V. For example, while the laser processing head 14 is moved by the placement device 18, the measuring device 66 continuously measures the velocity V at a predetermined cycle (for example, 0.5 second). Thus, the measurement position of the measurement device 66 is relatively moved along the jet, and the measurement device 66 continuously measures the velocity V along the jet.

The measuring device 66 outputs the measured speed V to the control unit 62 as output data α (═ V), and the output data α and the distance d output from the measuring device 66 in this way_aIn relation to each otherCorresponding to the relationship between the velocity V and the position x shown in FIG. 3, that is, the output data α obtained by the measurer 66 is based on the distance d_aVaries to have a first peak α at a location corresponding to the first maximum 32_max1And a second peak α at a location corresponding to the second maximum point 34_max2。

The controller 62 outputs the first peak value α of the continuous output data α outputted from the measuring device 66_max1The position x taken as representing the first maximum point 32₁Will be the second peak α_max2Taken as a position x representing the second maximum point 34₂In this way, the control unit 62 functions as the position acquisition unit 68 that acquires information indicating the positions of the local maximum points 32 and 34 from the output data α.

Then, the control unit 62 measures the first peak value α_max1The distance d between the measuring position of the measuring instrument 66 (i.e., the position of the dummy processing portion 64 a) and the injection hole 28_aObtain the target distance d_T. The target distance d_TThe position of the first maximum point 32 with respect to the injection hole 28 is shown, and may be obtained using a known gap sensor, displacement meter, or the like, for example.

Then, the control unit 62 correlates the opening size Φ of the injection hole 28 at the time of measuring the velocity V with the supply pressure Ps to determine the target distance d_TThe data is made into a database and stored in a storage unit. The operator changes the opening size phi and the supply pressure Ps of the nozzle 24 in various ways, and the control unit 62 obtains the target distance d by the above-described method each time the opening size phi and the supply pressure Ps are changed_TAnd performing database formation. In addition, in the case where the injection hole 28 is circular, the opening size is a diameter.

The opening size phi, the supply pressure Ps, and the target distance d are shown in table 1 below_TExamples of databases of (2).

TABLE 1

In the database shown in Table 1, the opening of the nozzle 24 is specifiedThe port size phi is correlated with the supply pressure Ps to set a plurality of target distances d_TIn addition, the control section 62 will measure the second peak α_max2Distance d between the injection opening 28 and the measuring position of the measuring device 66_{a_2}Is obtained as the second target distance d_{T_2}The second target distance d may be similarly prepared_{T_2}A database of (2). Further, a database may be created for each type of assist gas (nitrogen, air, etc.).

The target distance d thus created_TThe database (2) is used for specifying a target position where the nozzle 24 is to be arranged when the laser processing system performs laser processing on the workpiece W, as will be described later. For example, when the opening diameter of the injection port 28 of the nozzle 24 used for laser processing is 4mm and the supply pressure Ps to the chamber 29 is 2.0MPa, d is_TSuch data as 10mm is used to determine the target position.

By measuring the velocity V of the jet of assist gas in this way, information indicating the positions of the local maximum points 32 and 34 can be obtained. With this configuration, the positions of the local maximum points 32 and 34 can be determined with high accuracy by measurement.

Further, the jet flow observing apparatus 60 has a dummy workpiece 64. Here, the assist gas is blown onto the workpiece W during actual laser processing. In the jet flow observing apparatus 60, the assist gas is blown onto the dummy workpiece 64 instead of the workpiece W, and the positions of the local maximum points 32 and 34 are measured from the velocity V measured at the position of the dummy processed portion 64 a. According to this configuration, since the positions of the local maximum points 32 and 34 can be measured in a state close to actual laser processing, the positions of the local maximum points 32 and 34 can be measured with higher accuracy.

Further, the dummy workpiece 64 has the same outer shape (size) as the workpiece W. According to this configuration, since the positions of the local maximum points 32 and 34 can be measured in a state closer to the actual laser processing, the positions of the local maximum points 32 and 34 can be measured with higher accuracy. Further, the dummy workpiece 64 may have an outer shape (size) different from that of the workpiece W. In this case, the dummy workpiece 64 may have the same thickness in the z-axis direction as the workpiece W and a portion 64a corresponding to the machining portion S. The positions of the local maximum points 32 and 34 may be obtained without using the dummy workpiece 64.

Next, the jet flow observation device 70 will be described with reference to fig. 6 and 7. The jet flow observation device 70 acquires the position x indicating the maximum points 32 and 34 described above₁、x₂The information of (1). The jet flow observation device 70 includes: control unit 72, measuring device 76, and placement device 18. Control unit 72 includes a processor and a storage unit (not shown), and controls measuring instrument 76 and placement device 18.

The configuration device 18 has: the work table 38, the y-axis moving mechanism 40, the x-axis moving mechanism 42, and the z-axis moving mechanism 44 are provided, and the object 74 is placed on the work table 38. The placement device 18 moves the laser processing head 14 in the x-axis, y-axis, and z-axis directions, thereby moving the nozzle 24 relative to the object 74.

The object 74 is formed with a circular through-hole 74 a. The opening size of the through-hole 74a is set to be substantially the same as the opening size of a through-hole which is estimated to be formed when the workpiece W is pierced by the laser beam emitted from the nozzle 24. The object 74 may have the same outer shape (size) as the workpiece W, or may have a different outer shape (size) from the workpiece W. The object 74 may have the same thickness in the z-axis direction as the workpiece W and a portion corresponding to the machining portion S.

The measuring instrument 76 is disposed adjacent to the through-hole 74a, and measures the sound pressure SP or the frequency f of the sound generated when the jet flow emitted from the emission port 28 of the nozzle 24 passes through the through-hole 74a and strikes the object 74. In the present specification, the term "sound pressure" of a sound includes, in addition to a sound pressure (unit: Pa), a sound pressure level (unit: dB), and a sound intensity (unit: W/m)²) And the like.

In addition, the "frequency" of a sound includes a frequency characteristic (i.e., a frequency spectrum) of the sound in addition to the frequency of the sound. The frequency characteristics include information such as a sound pressure level of at least one frequency component (for example, 1Hz) or an average sound pressure level of a predetermined frequency band (for example, 1kHz to 10 kHz). The measuring instrument 76 includes a microphone 76a for converting sound into an electric signal, and a frequency acquiring unit 76b for acquiring a frequency characteristic of the sound from the electric signal.

Next, the position x of the maximum points 32 and 34 is obtained using the jet flow observation device 70₁、x₂The method of (1) is explained. First, the control unit 72 operates the placement device 18 to place the laser processing head 14 at the measurement initial position. When the laser processing head 14 is disposed at the measurement initial position, as shown in fig. 6, the laser processing head 14 is positioned with respect to the object 74 such that the optical axis O of the laser processing head 14 passes through the through-hole 74 a. Further, a distance d between the ejection outlet 28 and the object 74_bIs an initial value d_b0。

As an example, the initial value d_b0The object 74 is set to be disposed at a position close to the emission port 28, such as the close region 36 in fig. 3. As another example, the initial value d_b0The object 74 is set to be disposed at a position sufficiently far downstream of the jet flow from the position where the maximum point (the second maximum point 34 in the example of fig. 3) farthest from the injection port 28 is estimated to exist.

Next, the control unit 72 sends a command to the assist gas supply device 16, and upon receiving the command, the assist gas supply device 16 supplies the assist gas to the chamber 29 at the supply pressure Ps. The nozzle 24 emits a jet of assist gas having maxima 32 and 34. Next, the control unit 72 operates the placement device 18 to move the laser processing head 14 in the z-axis direction so as to set the distance d between the object 74 and the injection hole 28_bA change occurs.

For example, the initial value d is set as described above_b0When the object 74 is set to be disposed at the position close to the injection hole 28, the control unit 72 operates the disposition device 18 to move the laser processing head 14 in the positive z-axis direction so as to increase the distance d_b。

As another example, at the above-mentioned initial value d_b0When the object 74 is set to be disposed downstream of the maximum point farthest from the emission opening 28, the control unit 72 operates the disposition device 18 to move the laser processing head 14 in the negative z-axis direction so as to reduce the distance d_b。

While the placement device 18 moves the laser processing head 14 in the z-axis direction and moves the nozzle 24 closer to or away from the object 74, the control unit 72 sends a command to the measurement device 76 to cause the measurement device 76 to continuously measure the sound pressure SP or the frequency f. for example, while the placement device 18 moves the laser processing head 14, the measurement device 76 continuously measures the sound pressure SP or the frequency f at a predetermined cycle (for example, 0.5 seconds). the measurement device 66 sequentially outputs the measured sound pressure SP or the frequency f to the control unit 72 as output data β (SP or f).

Here, the sound pressure SP and the frequency f of the sound generated by the jet impinging on the object 74 when passing through the through-hole 74a are highly correlated with the flow velocity Vs of the assist gas. Specifically, the sound pressure (peak value, effective value, etc.) of the sound generated by the jet impinging on the object 74 and the frequency characteristic (for example, the sound pressure level of at least one frequency component) of the sound are highly correlated with the flow velocity Vs of the assist gas.

Thus, the obtained output data β and the distance d_bCorresponding to the graph shown in fig. 3, i.e. the output data β from measurer 76 is dependent on the distance d_bAnd instead has a first peak β at a location corresponding to the first maximum 32_max1And a second peak β at a location corresponding to the second maximum point 34_max2。

Control unit 72 calculates first peak value β of continuous output data β outputted from measuring instrument 76_max1The position x taken as representing the first maximum point 32₁Will be the second peak β_max2Taken as a position x representing the second maximum point 34₂In this way, the control unit 72 functions as the position acquisition unit 78 that acquires information indicating the positions of the local maximum points 32 and 34 from the output data β.

Then, the control unit 72 measures the first peak value β_max1Distance d between object 74 and exit opening 28_bObtain the target distance d_T. The target distance d_TThe position of the first maximum point 32 with respect to the emission hole 28 is shown, and may be obtained by using a known gap sensor or the like, for example.

Then, the control unit 72 correlates the opening size Φ of the injection hole 28 when the sound pressure SP and the frequency f are measured with the supply pressure Ps to determine the target distance d_TAnd a first peak β_max1And (6) database formation. The opening size phi is shown in Table 2 belowSupply pressure Ps, first peak value β_max1And a target distance d_TExamples of databases of (2).

TABLE 2

In the database shown in table 2, the first peak β is set by correlating the opening size Φ of the nozzle 24 with the supply pressure Ps_max1(sound pressure level) and target distance d_TIn addition, the control section 72 will measure the second peak β_max2Distance d between ejection opening 28 and object 74_{b_2}Is obtained as the second target distance d_{T_2}The second target distance d may be similarly prepared_{T_2}A database of (2).

Further, the database may be created for each type of assist gas (nitrogen, air, etc.). The target distance d thus created_TThe database (2) is used for specifying a target position where the nozzle 24 is to be arranged when the laser processing system performs laser processing on the workpiece W, as will be described later.

As described above, according to the jet flow observation device 70, the position x indicating the local maximum points 32 and 34 can be obtained from the sound of the jet flow of the assist gas hitting the object 74₁、x₂The information of (1). With this configuration, the position x of the local maximum points 32 and 34 can be accurately obtained by measurement₁、x₂. As will be described later, the jet flow observation device 70 can acquire the position x indicating the local maximum points 32 and 34 during the laser processing₁、x₂The information of (1).

Next, the jet flow observation device 80 will be described with reference to fig. 8 and 9. The jet flow observation device 80 obtains the position x of the first local maximum point 32 by a predetermined calculation₁. The jet flow observation device 80 includes a control unit 82 and a measurement instrument 84. The control unit 82 includes a processor and a storage unit (not shown), and controls the measuring unit 84.

The measuring device 84 measures the supply flow rate Vv of the assist gas supplied from the assist gas supply device 16 to the chamber 29. The measuring instrument 84 is provided in the gas supply pipe 30, and measures a flow rate Vv of the assist gas flowing in the gas supply pipe 30 from the assist gas supply device 16 toward the chamber 29.

Next, the position x of the first maximum point 32 is obtained by the jet flow observation device 80₁The method of (1) is explained. First, the control unit 82 sends a command to the assist gas supply device 16, and the assist gas supply device 16 supplies the assist gas to the chamber 29 in response to the command. The nozzle 24 emits a jet of assist gas having maxima 32 and 34.

Next, the control unit 82 sends a command to the measuring device 84, and the measuring device 84 measures the supply flow rate Vv from the auxiliary gas supply device 16 to the chamber 29 in response to the command. The measuring device 84 outputs output data (measurement value) of the supply flow rate Vv to the control unit 82. Next, the control unit 82 calculates the distance d from the emission hole 28 to the first local maximum point 32 using the output data Vv from the measuring device 84 and the following equation 1_cPosition x as the first maximum point 32₁The information of (1).

d_c＝0.67×φ×(ρVs²/2)^1/2DEG (mathematic formula 1)

Here, #denotesan opening size of the injection hole 28, ρ denotes a viscosity coefficient of the assist gas, and Vs denotes a flow velocity Vs of the assist gas obtained from the output data Vv and the opening size Φ. In this way, the control unit 82 functions as a position acquisition unit 86, and the position acquisition unit 86 acquires the position x of the first local maximum point 32 from the output data Vv of the measuring instrument 84 by calculation₁。

With the jet flow observation device 80, the position x of the first maximum point 32 can be obtained with high accuracy and quickly by calculation₁. As will be described later, the jet flow observation device 80 can acquire the position x of the first local maximum point 32 in real time during the laser processing₁。

Next, the laser processing system 100 will be explained with reference to fig. 10 and 11. The laser processing system 100 includes: a laser oscillator 12, a laser processing head 14, an auxiliary gas supply device 16, a placement device 18, and a control unit 102. The control unit 102 includes a processor (not shown) and a storage unit 104, and controls the laser oscillator 12, the laser processing head 14, the assist gas supply device 16, and the arrangement device 18. The storage unit 104 stores a database 106. The database 106 is, for example, a database as shown in table 1 or table 2 described above.

Next, the operation of the laser processing system 100 will be described. First, the control unit 102 obtains the opening size Φ of the injection port 28 of the nozzle 24 to be used and the set value of the supply pressure Ps of the assist gas from the assist gas supply device 16 to the chamber 29, and reads out and obtains the corresponding target distance d in the database 106 from the storage unit 104 based on the opening size Φ and the set value of the supply pressure Ps_T。

Next, the control unit 102 operates the placement device 18 to move the laser processing head 14 relative to the workpiece W, and moves the distance d between the injection hole 28 and the processing site S and the target position d_TThe nozzle 24 is arranged at a consistent target position. In this way, the target position is specified using the database 106, the control unit 102 functions as a movement control unit 108, and the movement control unit 108 controls the placement device 18 (i.e., the movement mechanisms 40, 42, and 44) to place the nozzle 24 at the target position.

Next, the control unit 102 operates the assist gas supply device 16 to supply the assist gas to the chamber 29 at the supply pressure Ps, and the nozzle 24 emits a jet of the assist gas having the local maximum points 32 and 34 of the velocity V. Next, the control unit 102 operates the laser oscillator 12 to emit the laser beam from the emission port 28, and operates the lens driving unit 23 to adjust the position of the optical lens 22 in the optical axis O direction so that the focal point of the emitted laser beam is disposed at the processing site S.

As a result, a through-hole is formed in the machining portion S of the workpiece W by the laser beam, and the control unit 102 operates the placement device 18 in accordance with the machining program stored in the storage unit 104, and performs laser machining (specifically, laser cutting) on the workpiece W while moving the nozzle 24 relative to the workpiece W. At this time, the machining site S of the workpiece W is disposed in the first mach disk region 33 (specifically, the position of the first local maximum point 32) of the jet of the assist gas.

According to the laser processing system 100, the assist gas can be effectively used to effectively blow away the material of the workpiece W melted by the laser beam. Further, since the generation of the plasma described above can be suppressed, the finishing quality of the processing site S of the workpiece W can be improved, and the contamination of the components of the laser processing head 14 can be suppressed.

In the laser processing system 100, the target position at which the nozzle 24 should be arranged when the workpiece W is processed is determined using the database 106 of the positions of the first local maximum points 32. According to this structure, the laser processing can be started by positioning the nozzle 24 and the workpiece W at the target position more quickly and easily.

In the laser processing system 100, the storage unit 104 may be set as a different element from the control unit 102. In this case, the storage unit 104 may be built in an external device (such as a server) communicably connected to the control unit 102, or may be a storage medium (such as a hard disk or a flash memory) externally attachable to the control unit 102. Further, the control unit 102 may fix the distance between the injection port 28 and the jig W when the workpiece W is laser-machined.

Next, the laser processing system 110 will be described with reference to fig. 12 and 13. The laser processing system 110 includes: a laser oscillator 12, a laser processing head 14, an auxiliary gas supply device 16, a placement device 18, a measuring device 76, and a control unit 112.

The control unit 112 has a processor and a storage unit 104, and controls the laser oscillator 12, the laser processing head 14, the assist gas supply device 16, the placement device 18, and the measuring device 76. The database 106 shown in table 2 is stored in the storage unit 104. The control unit 112 functions as the position acquiring unit 78 described above. That is, in the laser processing system 110, the placement device 18, the measurement instrument 76, and the control unit 112 constitute the jet flow observation device 70 described above.

Next, the operation of the laser processing system 110 will be described with reference to fig. 14. When receiving a machining start command from an operator, a host controller, or a machining program, the control unit 112 starts the flow shown in fig. 14.

In step S1, the control unit 112 positions the nozzle 24 at the initial target position with respect to the machining site S. Specifically, the control unit 112 obtains the opening size Φ of the injection hole 28 of the nozzle 24 to be used, andthe set value of the supply pressure Ps of the assist gas to the chamber 29 is read from the set values of the opening size φ and the supply pressure Ps, and the corresponding target distance d in the database 106 is acquired_T. Next, the control unit 112 functions as the movement control unit 108, and operates the placement device 18 to move the laser processing head 14 relative to the workpiece W, and the distance d between the injection hole 28 and the processing site S and the target distance d_TThe consistent initial target position configures the nozzle 24.

In step S2, the control unit 112 supplies the assist gas from the assist gas supply device 16 to the chamber 29 at the supply pressure Ps, and emits the jet of the assist gas from the injection port 28. The control unit 112 operates the laser oscillator 12 to emit the laser beam from the emission port 28, and operates the lens driving unit 23 to adjust the position of the optical lens 22 in the optical axis O direction so that the focal point of the emitted laser beam is disposed at the processing site S. As a result, a through hole H (fig. 12) is formed in the workpiece W, and the jet flows through the through hole H. The through hole H corresponds to the through hole 74a described above.

In step S3, control unit 112 starts the measurement by measuring instrument 76. Specifically, the control unit 112 transmits a command to the measuring instrument 76, and upon receiving the command, the measuring instrument 76 continuously (for example, at a predetermined cycle) measures the sound pressure SP or the frequency f of the sound generated by the jet flow ejected from the ejection port 28 of the nozzle 24 impacting the workpiece W when passing through the through-hole H.

The control unit 112 functions as the position acquisition unit 78, and serves as the position x indicating the first local maximum point 32₁The output data β of the sound pressure SP or the frequency f are sequentially acquired from the measuring instrument 76 and stored in the storage unit 104, and as described in connection with the jet flow observation device 70, the information includes the first peak β_max1Corresponding to the position x representing the first maximum point 32, output data β of₁The information of (1).

In step S4, the control unit 112 starts laser processing. Specifically, the control unit 112 operates the placement device 18 in accordance with the machining program, moves the nozzle 24 relative to the workpiece W, and performs laser machining (laser cutting) on the workpiece W with the laser beam emitted from the emission port 28.

In step S5The control unit 112 determines whether the output data β most recently acquired by the measuring device 66 is larger than a preset lower limit value β_minSmall, the lower limit value β_minThe boundary for defining whether the jet flow velocity V emitted from the nozzle 24 is abnormally low is determined in advance by an operator.

Here, it is assumed that the velocity V of the jet flow may be significantly lower than the reference value when the injection port 28 is clogged or the operation of the auxiliary gas supply device 16 is abnormal (for example, short of air). in this case, the output data β obtained by the measurement device 66 is different from (specifically, is smaller than) the reference data measured by the measurement device 66 when the jet flow is normally injected from the nozzle 24.

The control unit 112 determines whether the output data β is less than the lower limit β_minThe control unit 112 functions as an abnormality determination unit 113 that determines whether or not the output data β is different from the reference data.

When controller 112 determines that output data β is greater than lower limit value β_minIf small (i.e., yes), the process proceeds to step S6, while the control unit 112 determines that the output data β is the lower limit β_minIn the case of the above (i.e., no), the process proceeds to step S8. In step S6, the control unit 112 sends a command to the laser oscillator 12 to stop the laser oscillation operation, thereby stopping the laser processing of the workpiece W.

In step S7, the control unit 112 outputs a warning. For example, the control unit 112 generates "there is an abnormality in the injection of the assist gas. Please check the opening size of the nozzle or the supply pressure of the auxiliary gas "or the like. The control unit 112 outputs the warning through a speaker or a display unit (not shown). In this way, the control unit 112 functions as a warning generation unit 118 that generates a warning.

The speaker or the display unit may be provided in the control unit 112, or may be provided outside the control unit 112. The operator can intuitively recognize the presence of an abnormality in the nozzle 24 or the supply of the assist gas by the warning, and can take measures against the replacement of the nozzle 24 or an abnormality (e.g., a shortage) in the operation of the assist gas supply device 16. After executing step S7, the control unit 112 ends the flow shown in fig. 14.

In step S8, control unit 112 determines whether or not output data β most recently acquired by measuring instrument 76 is greater than a preset threshold β_thSmall, the threshold β_thIs greater than the above lower limit value β_minLarge value, for example, the threshold value β_thMay be set to multiply a prescribed coefficient a (0 < a < 1) by the first peak β stored in the database 106_max1The resulting value.

For example, when the opening size Φ is set to 1.0mm, the supply pressure Ps is set to 2.0MPa, and a is set to 0.95 using the database 106 shown in table 2, the threshold value β is set_thFig. 16 schematically shows the relationship between the output data β and the position x of the machining portion S of the workpiece W with respect to the injection hole 28, and the relationship between the output data β and the position x corresponds to the graph shown in fig. 3.

Slave threshold β_thTo a first peak β_max1Corresponds to position x₃And position x₄The position range 114 in between. The position x of the first maximum point 32 is included in the position range 114₁. Here, in step S1 described above, the distance d between the injection hole 28 and the processing site S and the target distance d of the nozzle 24 are set_TA consistent initial target position. Therefore, it is understood that the processing site S is arranged at the position x of the first local maximum point 32 after the end of step S1₁Or its vicinity.

However, when the laser processing of the workpiece W is performed, the distance d between the emission port 28 and the processing portion S may vary for some reason, for example, the distance d may vary due to a step portion formed in the processing portion of the workpiece W, and thus, when the distance d varies, the output data β of the measuring instrument 76 may fall below the threshold value β_th。

In step S8, the controller 112 determines that the output data β is greater than the threshold β_thIf small (i.e., yes), the process proceeds to step S9, while the control unit 112 determines that the output data β is the threshold β_thIn the case of the above (i.e., no), the process proceeds to step S15.

In step S9, the control unit 112 changes the target position of the nozzle 24. Specifically, the control unit 112 changes the target position of the nozzle 24 at the start time of step S9 to a new target position after moving in the negative z-axis direction or the positive z-axis direction. The control unit 112 functions as the movement control unit 108 to operate the placement device 18 and move the nozzle 24 in the negative z-axis direction or the positive z-axis direction to place it at the new target position. As a result, the nozzle 24 approaches or moves away from the workpiece W.

In step S10, control unit 112 determines whether or not output data β acquired by measuring instrument 66 before step S9 is increased as compared to output data β acquired by measuring instrument 66 after the end of step S9, and here, if output data β is decreased as a result of moving nozzle 24 in step S9, the position of workpiece W (specifically, machining point S) is separated from position range 114 in the drawing shown in fig. 16, and therefore, in this case, in order to store the position of workpiece W in position range 114, it is necessary to reverse the direction in which nozzle 24 is moved in step S9.

On the other hand, assuming that the output data β is increased as a result of the movement of the nozzle 24 at step S9, the position of the workpiece W is close to the position x in the diagram shown in fig. 16₁. Therefore, in this case, it is not necessary to change the direction in which the nozzle 24 is moved in step S9.

In step S10, control unit 112 proceeds to step S12 when it determines that output data β acquired by meter 66 before step S9 is increased (i.e., yes) compared to output data β acquired by meter 66 after the end of step S9, and on the other hand, control unit 112 proceeds to step S11 when it determines that output data β acquired by meter 66 before step S9 is decreased (i.e., no) compared to output data β acquired by meter 66 after the end of step S9.

In step S11, the control unit 112 reverses the direction of moving the nozzle 24. For example, when the nozzle 24 is moved in the z-axis negative direction in the previous step S9, the control unit 112 reverses the direction in which the nozzle 24 is moved in the subsequent step S9 to the z-axis positive direction. Then, the control section 112 returns to step S9.

In step S12, controlSection 112 determines whether or not output data β most recently acquired by measuring instrument 76 is threshold value β_thIn this way, when the control unit 112 determines that the output data β is the threshold β_thIn the above case (i.e., yes), the process proceeds to step S15, and on the other hand, the control unit 112 determines that the output data β is still larger than the threshold β_thIf small (i.e., no), the process proceeds to step S13.

In step S13, control unit 112 determines whether or not the number of times n determined as NO (NO) in step S12 exceeds a preset maximum number of times n_max. The maximum number n_maxDetermined by the operator as an integer of 2 or more (e.g., n)_max10). When the control unit 112 determines that the number n exceeds the maximum number n_maxIf yes, the process proceeds to step S14. On the other hand, the control unit 112 determines that the number n does not exceed the maximum number n_max(i.e., no), the process returns to step S9.

In this way, by executing the loop of steps S9 to S13 in fig. 14, the control unit 112 changes the target position of the nozzle 24 so that the output data β of the measuring instrument 76 is contained in the range 116 of the output data indicating the position range 114 during the machining of the workpiece W, and performs feedback control on the placement device 18 in accordance with the changed target position to move the nozzle 24.

That is, the target position of the nozzle 24 is determined based on the position x representing the first local maximum point 32₁First peak β of the output data β_max1The feedback control allows the machining site s to be continuously arranged in the first mach disk region 33 during the machining of the workpiece W, that is, the first mach disk region 33 in the laser machining system 110 may be defined to pass the threshold value β_thBut rather the area of the defined location range 114.

On the other hand, if the determination at step S13 is yes, the control unit 112 executes an abnormality processing routine at step S14. Although the feedback control of steps S9-S13 is repeatedly performed for the number of times n_maxThen, but not β ≧ β_thIn this case, the above-described abnormality such as clogging or lack of air may occur.

Here, the characteristic shown in fig. 16 is that the injection is performed in a state where no abnormality occursReference data measured by the measuring instrument 76 when the jet stream is normally emitted from the port 28, the first peak β_max1Constituting reference data, and setting a threshold β for the reference data_th. Therefore, the range 116 in fig. 16 is a range of output data indicating the position range 114, which is determined from the reference data.

The control unit 112 functions as the abnormality determination unit 113, and when the determination at step S13 is yes, it determines that the output data β of the measuring instrument 76 is different from the reference data, and executes the abnormality processing routine of step S14, this step S14 will be described with reference to fig. 15, and in the flow shown in fig. 15, the same procedures as those in the flow shown in fig. 14 are assigned the same step numbers, and overlapping description will be omitted.

In step S21, the control unit 112 sends a command to the assist gas supply device 16 to change the supply pressure Ps of the assist gas to the chamber 29. The control unit 112 increases the supply pressure Ps in stages at a predetermined pressure (for example, 0.2MPa) each time step S21 is executed. In this way, the control unit 112 functions as the pressure adjustment unit 115 that changes the supply pressure Ps.

Next, control unit 112 executes step S12 described above, and determines whether or not output data β most recently acquired by measuring instrument 76 is threshold β_thThe above. If the determination is yes, the control unit 112 proceeds to step S15 in fig. 14, and if the determination is no, the control unit proceeds to step S22.

In step S22, control unit 112 determines whether or not number m of times determined as no in step S12 in fig. 15 exceeds preset maximum number m of times_max. The maximum number m_maxIs determined by an operator to be an integer of 2 or more (e.g., m)_max5). When determining that the number m exceeds the maximum number m, the control unit 112_maxIf yes, the process proceeds to step S6 in fig. 14. On the other hand, the control unit 112 determines that the number m does not exceed the maximum number m_max(i.e., no), the process returns to step S21.

Referring again to fig. 14, in step S15, the control unit 112 determines whether or not the laser processing of the workpiece W is completed, for example, based on the processing program. When determining that the laser processing is completed (i.e., yes), the control unit 112 sends a command to the laser oscillator 12 to stop the laser oscillation operation, and ends the flow shown in fig. 14. On the other hand, when determining that the laser processing is not completed (i.e., no), the control unit 112 returns to step S8.

As described above, the control unit 112 feedback-controls the position of the nozzle 24 so as to continue the arrangement of the machining site S in the first mach disk region 33 based on the output data β obtained by the measuring instrument 76 during the machining of the workpiece W, and according to this configuration, even if the distance d between the injection port 28 and the machining site S changes for some reason, the workpiece W can be laser-machined while the machining site S is arranged in the first mach disk region 33, and therefore, the assist gas can be effectively used.

Further, the control unit 112 determines that the jet flow is abnormal by executing step S14. If an abnormality such as a blockage or a gas shortage occurs, the velocity V of the jet flow emitted from the emission port 28 hardly changes even if the supply pressure Ps of the auxiliary gas supply device 16 to the cavity 29 is changed.

That is, in this case, output data β of measurement instrument 76 hardly changes, and even if the loop of steps S21 to S22 in FIG. 15 is repeatedly executed, β ≧ β does not occur_th(i.e., yes at step S12 in fig. 15).

The control unit 112 functions as the abnormality determination unit 113, and repeatedly executes the loop specification times m of steps S21 to S22_maxBut not β ≧ β_thIn the case where the output data β is determined to be different from the reference data, a warning is output in step S7 in fig. 14, and this configuration enables the operator to intuitively recognize that there is an abnormality in the nozzle 24 or the supply of the assist gas, and to take measures against the replacement of the nozzle 24 or an abnormality (shortage) in the operation of the assist gas supply device 16.

On the other hand, the velocity V of the jet flow emitted from the injection port 28 may be slightly lower than the reference value due to slight abnormalities such as an error in the opening size or the length in the z-axis direction of the injection port 28, an inclination of the injection port 28 with respect to the z-axis, or an error in the design size of the internal space (cavity 29) of the nozzle 24. In the case of such a slight abnormality, the supply pressure Ps may be changed in accordance with the injectionAlthough the flow speed varies, even if the feedback control of steps S9 to S15 is repeatedly executed, it is not β ≧ β_thThe determination at step S13 is yes.

In the laser processing system 110, in step S14, β ≧ β is made by executing step S21_thIn this case, the control unit 112 continues the machining of the workpiece W. According to this configuration, even when the velocity V of the jet flow is reduced from the reference value due to a slight abnormality such as a dimensional error, the machining of the workpiece W can be continued with the jet flow blown to the machining site S at a sufficiently high velocity V by changing (specifically, increasing) the supply pressure Ps.

In addition, the control unit 112 may sequentially store the distance d between the emission port 28 and the processing site S at that time, every time it is determined as yes in step S12 in the first laser processing step. The control unit 112 may set the initial target position of step S1 of the second laser processing step to be executed next to the first laser processing step, based on the distance d stored in the first laser processing step. For example, the control unit 112 may set the average value of the distances d stored in the first laser processing step or the last stored distance d as the initial target position of the second laser processing step.

As a modification of laser processing system 110, measuring device 66 described above may be applied instead of measuring device 76. In this case, the measuring instrument 66 is configured to measure the velocity V of the jet flow at the position of the machining site S (or at a position slightly offset from the machining site S in the direction of the injection port 28) in a non-contact manner. The measuring device 66 applied to the laser processing system 110, the placement device 18, and the control unit 112 constitute the above-described jet observation device 60.

In the present modification, the controller 112 may execute the flow shown in fig. 14 and 15 based on the output data α of the measuring device 66 instead of the output data β to laser-machine the workpiece W in a state where the workpiece W is disposed in the first mach disk region 33.

Next, the laser processing system 120 will be explained with reference to fig. 17 and 18. The laser processing system 120 includes: a laser oscillator 12, a laser processing head 14, an auxiliary gas supply device 16, a placement device 18, a dummy workpiece 64, a measuring device 66, and a control section 122.

The control unit 122 includes a processor and a storage unit (not shown), and the control unit 122 controls the laser oscillator 12, the laser processing head 14, the assist gas supply device 16, the arrangement device 18, and the measuring device 66. The control unit 122 functions as the position acquisition unit 68 described above. That is, the placement device 18, the dummy workpiece 64, the measuring instrument 66, and the control unit 122 constitute the above-described jet flow observation device 60.

Next, the operation of the laser processing system 120 will be described. First, the control unit 122 acquires the position x indicating the first local maximum point 32₁Specifically, the control unit 122 functions as the position acquiring unit 68, and the first peak α of the output data α of the measuring instrument 66 is obtained from the jet flow observing device 60 by the method described in connection with the above-described jet flow observing device 60_max1Obtaining a target distance d_T。

Next, the control unit 122 disposes the nozzle 24 at the target position. Specifically, the control unit 122 functions as the movement control unit 108, and operates the placement device 18 to move the laser processing head 14 relative to the workpiece W, and the distance d between the injection hole 28 and the processing site S and the target distance d_TThe nozzle 24 is arranged at a consistent target position.

Next, the control unit 122 operates the assist gas supply device 16 to supply the assist gas to the chamber 29 at the supply pressure Ps, and emits the jet of the assist gas from the emission port 28. The control unit 122 operates the laser oscillator 12 to emit the laser beam from the emission port 28, and operates the lens driving unit 23 to adjust the position of the optical lens 22 in the optical axis O direction so that the focal point of the emitted laser beam is disposed at the processing site S.

In this state, the control unit 122 operates the placement device 18 in accordance with the machining program, and performs laser machining (laser cutting) on the workpiece W while moving the nozzle 24 relative to the workpiece W. At this time, the machining site S of the workpiece W is disposed in the first mach disk region 33 of the jet of the assist gas.

As described above, before the machining of the workpiece W, the control unit 122 acquires the position of the first local maximum point 32 by the jet flow observation device 60Put x₁At the position x based on the acquired first local maximum 32₁The workpiece W is laser-processed in a state where the nozzle 24 is disposed at the specified target position. According to this configuration, the machining site S can be disposed in the first mach disk region 33 during machining of the workpiece W, and therefore the assist gas can be effectively used.

Further, according to the laser processing system 120, even when the opening size Φ of the injection hole 28 and the supply pressure Ps of the assist gas are unknown, the position x of the first maximum point 32 can be acquired by the jet flow observation device 60 before the processing of the workpiece W₁Can be determined from the position x of the first maximum point 32₁To set the target position of the nozzle 24.

Next, the laser processing system 130 will be described with reference to fig. 19 and 20. The laser processing system 130 includes: a laser oscillator 12, a laser processing head 14, an auxiliary gas supply device 16, a placement device 18, a measuring device 84, and a control unit 132.

The control unit 132 includes a processor and the storage unit 104, and the control unit 132 controls the laser oscillator 12, the laser processing head 14, the assist gas supply device 16, the arrangement device 18, and the measuring device 84. The database 106 shown in table 1 described above is stored in the storage unit 104. The control unit 132 functions as the position acquisition unit 86 described above. That is, the measurement instrument 84 and the control unit 132 constitute the above-described jet flow observation device 80.

Next, the operation of the laser processing system 130 will be described with reference to fig. 21. When the control unit 132 receives a machining start command from an operator, a host controller, or a machining program, the flow shown in fig. 21 is started. In the flow shown in fig. 21, the same processes as those in the flow shown in fig. 14 are denoted by the same step numbers, and redundant description is omitted.

After steps S1 and S2 are performed, in step S31, the control portion 132 starts measuring the supply flow rate Vv of the assist gas supplied from the assist gas supply device 16 to the chamber 29. Specifically, control unit 132 sends a command to measuring device 84 to cause measuring device 84 to continuously (e.g., at a predetermined cycle) measure supply flow rate Vv. Further, the control unit 132 starts measuring the distance d between the injection hole 28 and the processing site S. As described above, the distance d can be obtained using a known gap sensor or the like.

After step S4, in step S32, the controller 132 obtains the position x of the first local maximum point 32₁. Specifically, the control unit 132 functions as the position acquisition unit 86, and calculates the distance d from the emission hole 28 to the first local maximum point 32 using the output data Vv most recently acquired by the measuring instrument 84 and the above equation 1_cAs the position x of the first maximum point 32₁The information of (1).

In step S33, the control unit 132 determines the distance d and the distance d_cWhether the difference delta is larger than a predetermined threshold delta_thIs large. Specifically, the control unit 132 calculates the distance d between the injection hole 28 and the processing site S, which is measured most recently, and the distance d obtained in the most recent step S32_cDifference delta (═ d-d)_c)。

The control unit 132 determines that the difference δ is an absolute value (| d-d)_cI) ratio threshold value delta_thIf large (i.e., yes), the process proceeds to step S34. On the other hand, when the control unit 132 determines that the absolute value of the difference δ is the threshold δ_thThereafter (i.e., no), the process proceeds to step S15. The threshold value delta_thAs determined by the operator.

In step S34, the control unit 132 changes the target position of the nozzle 24. Specifically, when the difference δ calculated in the previous step S33 is a positive value, the control unit 132 changes the target position of the nozzle 24 at the start time of step S34 to a new target position after moving in the negative z-axis direction.

Then, the control unit 132 functions as the movement control unit 108, and operates the placement device 18 to move the nozzle 24 in the negative z-axis direction in order to place the nozzle at the new target position. As a result, the nozzle 24 approaches the workpiece W, so that the distance d between the injection port 28 and the processing site S decreases.

On the other hand, when the difference δ calculated in step S33 is a negative value, the control unit 132 changes the target position of the nozzle 24 at the start time point of step S34 to a new target position after moving in the positive z-axis direction. Then, the control unit 132 operates the placement device 18 to move the nozzle 24 in the positive z-axis direction to place it at the new target position. As a result, the nozzle 24 is spaced away from the workpiece W, and the distance d between the injection port 28 and the machining site S is increased. After step S34 is performed, the control section 132 returns to step S32.

On the other hand, if it is determined as no in step S33, the control unit 132 executes step S15 described above, and if it is determined as yes, sends a command to the laser oscillator 12 to stop the laser oscillation operation, thereby ending the flow shown in fig. 21, whereas if it is determined as no, returns to step S32.

In this way, in the laser processing system 130, the position x of the first maximum point 32 obtained by the jet flow observation device 80 during the laser processing is used as the basis₁The target position of the nozzle 24 is changed, and the arrangement device 18 is feedback-controlled according to the changed target position to move the nozzle 24.

That is, the target position of the nozzle 24 is based on the position x of the first local maximum 32₁And is determined as a prescribed range (satisfying 0. ltoreq. delta_thRange of (d). By this feedback control, the machining site S can be continuously arranged in the first mach disk region 33 during the machining of the workpiece W. That is, the first mach disk region 33 in the laser processing system 130 may be defined as the position x from the first local maximum 32₁The distance delta satisfies the condition that delta is more than or equal to 0 and less than or equal to delta_thThe range area of (1).

According to the laser processing system 130, even if the distance d between the emission port 28 and the processing location S is changed for some reason, the workpiece W can be laser processed in a state where the processing location S is disposed in the first mach disk region 33. Therefore, the assist gas can be effectively utilized.

Next, the jet flow adjusting device 140 will be described with reference to fig. 22. The jet flow adjusting device 140 adjusts the position x of the maximum points 32 and 34 of the jet flow emitted from the emission port 28 of the nozzle 24₁、x₂And has a housing 142 and a housing driving section 144. The housing 142 is a cylindrical member having a radially inner dimension.

The housing 142 is formed of a flexible cylindrical member having a radius R as a radially inner dimension. The cylindrical member is, for example, a wool material, a resin material, or a rubber material. The housing 142 is arranged substantially concentrically with the ejection port 28 with respect to the optical axis O, and the housing 142 has: an end 142a in the z-axis negative direction, and an end 142b opposite to the end 142 a.

The end portion 142a is mounted on the mounting surface of the work table 38. The end 142b is disposed at a position farther from the injection port 28 in the positive z-axis direction. In other words, the housing 142 has a sufficient length in the z-axis direction so that the end 142b is always disposed farther away from the injection port 28 in the positive z-axis direction during the workpiece machining.

The housing drive section 144 includes: a mechanism unit 146 for deforming the casing 142 to change the radius R of the casing 142, and a power unit 148 for generating power for driving the mechanism unit 146. Various modes are conceivable as the housing 142 and the mechanism portion 146 capable of changing the radius R. Hereinafter, examples of the housing 142 and the mechanism unit 146 will be described with reference to fig. 23 and 24. In fig. 23 and 24, the housing 142 is shown by a broken line from the viewpoint of easy understanding.

The mechanism unit 146A shown in fig. 23 is a so-called iris diaphragmechanicism (iris diaphragmechanism) used for a camera or the like. Specifically, the mechanism portion 146A includes a plurality of vanes 150, and these vanes 150 operate so as to move radially inward while rotating in the circumferential direction. The outer case 142 is connected to inner edges of the plurality of blades 150, and deforms to reduce the diameter and expand the diameter in accordance with the operation of the blades 150. The power unit 148 includes, for example, a servomotor, and drives the mechanism unit 146A to reduce and expand the diameter of the housing 142.

On the other hand, the mechanism unit 146B shown in fig. 24 includes: an arm portion 152 extending in the circumferential direction around the optical axis O, and a gear 156 provided in an overlapping region 154 of the arm portion 152. On the circumferential surfaces of the arm portions 152 facing each other in the overlapping region 154, teeth are formed, and the gear 156 is engaged with the teeth. The housing 142 is connected to the inner periphery of the arm portion 152 outside the overlap region 154.

In the state shown in fig. 24 (a), the length of the overlapping region 154 of the arm portion 152 in the circumferential direction is increased, and a slack 158 is formed in the housing 142. From the state shown in fig. 24 (a), as the gear 156 rotates in one direction, the overlapping region 154 of the arm portion 152 is narrowed, and along with this, the slack 158 of the housing 142 is gradually extended in the circumferential direction, and the housing 142 is expanded in diameter to the state shown in fig. 24 (b).

Conversely, from the state shown in fig. 24 (b), as the gear 156 rotates in the other direction, the overlapping area 154 of the arm portion 152 expands, and accordingly, the slack 158 of the housing 142 gradually expands, and the housing 142 reduces in diameter to the state shown in fig. 24 (a). The power unit 148 includes, for example, a servomotor, and rotationally drives the gear 156 to reduce and expand the diameter of the housing 142.

Referring again to fig. 22, jet flow adjustment apparatus 140 can adjust position x of first local maximum point 32 by changing radius R of housing 142₁And the position x of the second maximum point 34₂. The following pairs can thus adjust the position x of the maxima 32, 34₁、x₂The principle of (a) is explained.

As described above, the assist gas emitted from the emission port 28 is reflected at the boundary with the outside air, and forms a mach disk in the jet flow. When the housing 142 is provided, the atmosphere existing between the jet flow and the housing 142 is compressed by the jet flow, and the particle density of the atmosphere is increased.

When the assist gas is reflected at the boundary between the compressed air layers, the reflection angle and reflection position of the assist gas change, and as a result, the positions of the mach disks (i.e., the positions x of the local maximum points 32 and 34) formed in the jet flow are changed as compared with the case where the outer shell 142 is not provided₁、x₂) A change occurs.

When the internal dimension of the casing 142 is changed, the volume and particle density of the atmosphere existing between the jet and the casing 142 are changed, whereby the position of the mach disk formed in the jet can be changed. Using the principle as described above, the jet flow adjusting device 140 adjusts the positions x of the local maximum points 32 and 34 in the optical axis O direction₁、x₂。

Specifically, the jet flow adjustment device 140 reduces the diameter of the case 142 to set the position x of the local maximum points 32 and 34₁、x₂Displaced toward the downstream side of the jet flow (i.e., in a direction away from the injection port 28 along the optical axis O). On the other hand, the jet flow adjusting device 140 expands the diameter of the case 142 to increase the position x of the local maximum points 32 and 34₁、x₂Is displaced toward the upstream side of the jet flow.

According to the jet flow adjusting device 140, by changing the inner dimension (radius R) of the housing 142, the position x of the maximum point 32, 34 can be adjusted according to the variation of the distance d between the injection hole 28 and the machining site S during the machining of the workpiece₁、x₂So that the machining site S is disposed in the first mach disk region 33.

When the casing 142 is reduced in diameter while the supply pressure Ps to the chamber 29 formed inside the nozzle 24 having the predetermined opening diameter is constant, the position x of the local maximum point 32, 34 is set to be constant₁、x₂Is displaced to the downstream side of the jet flow, and the position x₁、x₂The velocity V of the jet increases. That is, the velocity V of the jet flow in the mach disk regions 33 and 35 where the workpiece W is disposed can be increased without changing the supply pressure Ps.

In other words, even if the supply pressure Ps is reduced, the velocity V of the jet flow in the mach disk regions 33 and 35 can be maintained by reducing the diameter of the casing 142. According to this configuration, since the consumption amount of the assist gas can be reduced, the cost can be suppressed. The housing driving unit 144 may be omitted, and the internal dimensions of the housing 142 may be manually changed.

Next, the laser processing system 160 will be explained with reference to fig. 25 and 26. The laser processing system 160 includes: a laser oscillator 12, a laser processing head 14, an auxiliary gas supply device 16, a placement device 18, a measuring device 84, a jet flow adjusting device 140, and a control unit 162.

The control unit 162 includes a processor and a storage unit 104, and controls the laser oscillator 12, the laser processing head 14, the assist gas supply device 16, the placement device 18, the measuring device 84, and the jet flow adjusting device 140 (specifically, the power unit 148). The storage unit 104 stores the database 106 shown in table 1. The control unit 162 functions as the position acquiring unit 86 described above. That is, the measurement instrument 84 and the control unit 162 constitute the above-described jet flow observation device 80.

Next, the operation of the laser processing system 160 will be described with reference to fig. 27. When the control unit 162 receives a machining start command from an operator, a higher controller, or a machining program, the flow shown in fig. 27 is started. In the flow shown in fig. 27, the same steps as those in the flow shown in fig. 21 are denoted by the same reference numerals, and redundant description thereof is omitted.

After the flow shown in fig. 27 is started, controller 162 executes steps S1 to S33 similar to the flow shown in fig. 21. If yes in step S33, the controller 162 controls the position x of the first local maximum point 32 in step S41₁. Specifically, the difference δ (═ d-d) calculated in step S33 is calculated_c) If the value is positive, the control unit 162 sends a command to the power unit 148 of the housing driving unit 144 to reduce the inner dimension (radius R) of the housing 142. Thereby, the position x of the first local maximum point 32₁Is displaced toward the downstream side of the jet flow.

On the other hand, when the difference δ calculated in the previous step S33 is a negative value, the control unit 162 operates the housing driving unit 144 to increase the inner dimension (radius R) of the housing 142. Thereby, the position x of the first local maximum point 32₁Is displaced toward the upstream side of the jet flow.

In this way, the control unit 162 functions as the maximum point control unit 164, and the maximum point control unit 164 determines the position x of the first maximum point 32 obtained by the position obtaining unit 86 in step S32 based on the position x₁Changes the internal dimensions of the housing 142, thereby controlling the position x of the first local maximum 32₁. After step S41 is performed, the control unit 162 returns to step S32.

According to the laser processing system 160, the machining site S can be continuously arranged in the first mach disk region 33 during the processing of the workpiece W by changing the internal dimension of the housing 142 without moving the nozzle 24. According to this configuration, even if the distance d between the injection hole 28 and the machining site S is changed for some reason, the workpiece W can be laser-machined while the machining site S is disposed in the first mach disk region 33. Therefore, the assist gas can be effectively utilized.

In addition, in the laser beamIn the tool system 160, the storage unit 104 may store a database in which a plurality of target distances d are stored in association with the opening size Φ of the nozzle 24, the supply pressure Ps, and the internal size (radius R) of the casing 142_T. In this case, in step S41, the controller 162 simply needs to adjust the opening diameter Φ, the supply pressure Ps, and the distance d calculated in step S32_cAs a target position distance d_TAnd applied to the database, the target internal dimensions of the housing 142 can be determined.

Then, in step S41, the control unit 162 operates the casing driving unit 144 to change the internal dimension of the casing 142 to the target internal dimension obtained from the database. This makes it possible to arrange the machining site S in the first mach disk region 33 with high accuracy.

The flow shown in fig. 27 may be executed by the laser processing system 130 described above. In this case, in step S41, the control unit 132 can control the position x of the local maximum point 32 or 34 by changing the supply pressure Ps to the chamber 29₁、x₂. Here, when the supply pressure Ps to the chamber 29 is increased, the position x of the local maximum points 32 and 34₁、x₂And is displaced toward the downstream side of the jet flow (i.e., in a direction away from the injection port 28 along the optical axis O).

On the other hand, when the supply pressure Ps to the chamber 29 is reduced, the position x of the local maximum points 32 and 34₁、x₂Is displaced toward the upstream side of the jet flow (i.e., in the direction approaching the ejection port 28 along the optical axis O). In step S41, the controller 132 calculates the difference δ (═ d-d) in step S33 before the calculation_c) If the value is positive, a command is sent to the auxiliary gas supply device 16 to increase the supply pressure P_s. Thereby, the position x of the first local maximum point 32₁Is displaced toward the downstream side of the jet flow.

On the other hand, when the difference δ calculated in the previous step S33 is a negative value, the control unit 132 sends a command to the assist gas supply device 16 to decrease the supply pressure P_s. Thereby, the position x of the first local maximum point 32₁Is displaced toward the upstream side of the jet flow. In this way, the control unit 132 functions as a maximum point control unit that controls the position acquisition unit 86 in step sPosition x of the first local maximum 32 acquired at S32₁To change the supply pressure P_sThereby controlling the position x of the first maximum point 32₁。

In addition, the placement device 18 is not limited to the above-described structure, and may have, for example: a workpiece table movable along an x-y plane, and a z-axis moving mechanism that moves the nozzle 24 along the z-axis. Alternatively, the placement device may not have a moving mechanism, and simply manually fix the nozzle 24 at an arbitrary position with respect to the workpiece W.

The dummy workpiece 64 and the measuring instrument 66 of the jet flow observation device 60 shown in fig. 4 may be in various forms. Examples of the dummy workpiece 64 and the measuring tool 66 will be described below with reference to fig. 28 and 29. In the example shown in fig. 28, the dummy workpiece 64 has a circular through-hole 64b formed at a position corresponding to the dummy processing portion 64 a. The opening size of the through-hole 64ba is set to be substantially the same as the opening size of a through-hole which is estimated to be formed when the workpiece W is pierced by the laser beam emitted from the nozzle 24.

The measuring device 66 includes a pair of columnar portions 170 and a hot wire 172. The pair of pillar portions 170 extend from the front surface 64c of the dummy workpiece 64 in the positive z-axis direction and are disposed to face each other. The heat wire 172 linearly extends between the pair of columnar portions 170, and its resistance value changes according to the velocity V of the jet flow emitted from the emission port 28.

Here, the length L of the hot wire 172 extending between the pair of columnar portions 170 (i.e., the distance between the pair of columnar portions 170) may be set to, for example, the opening size Φ of the injection hole 28 or less or the opening size of the through-hole 64ba or less. Alternatively, the hot wire 172 may be composed of a material having high rigidity. By setting the length L to be small or forming the heat wire 172 of a material having high rigidity in this manner, it is possible to prevent the heat wire 172 from being bent when the heat wire 172 is disposed in the jet flow.

Further, the distance from the surface 64c of the dummy workpiece 64 to the hot wire 172 may be set to, for example, 0.5mm or less. By setting the distance from the surface 64c to the hot wire 172 small in this manner, the velocity V of the jet can be measured at a position close to the machining site S of the workpiece W at which laser machining is performed.

In the example shown in fig. 29, the measuring tool 66 has a hot wire 174 extending to the through-hole 64 b. The length L of the hot wire 174 corresponds to the opening size of the through-hole 64 b. The hot wire 174 is disposed at the position of the surface 64c of the dummy workpiece 64. With such arrangement of the heat wire 174, the velocity V of the jet flow can be measured at a position close to the processing site S of the workpiece W at which the laser processing is performed. As described above, the measuring instrument 66 of fig. 28 and 29 constitutes a hot wire anemometer.

In the above-described embodiment, when the workpiece W is machined, the workpiece W may be disposed in the second mach disk region 35 (the second pole 34) or the nth mach disk region (n is an integer of 3 or more). Alternatively, instead of the above-described jet flow observation devices 60, 70, 80, for example, an image as shown in fig. 2 may be captured by a high-speed camera, and the position x of the local maximum point 32, 34 may be measured from the image₁、x₂。

The injection port 28 is not limited to a circular shape, and may have any shape such as a polygonal shape or an elliptical shape. Further, the features of the above-described various embodiments may be combined with each other. For example, the jet observation device 80 may be combined with the laser processing system 110 or 120, or the jet adjustment device 140 may be combined with the laser processing system 110 or 120.

The present disclosure has been described above with reference to the embodiments, but the embodiments described above do not limit the invention according to the claims.

Claims (6)

1. A laser processing system, characterized in that,

the laser processing system has: a nozzle having an ejection port for ejecting a jet of the assist gas along an optical axis of the laser beam, the nozzle forming a maximum point of a velocity of the jet at a position distant from the ejection port,

the laser processing system is configured to: in the process of processing the workpiece by the laser beam, the nozzle is arranged at a target position determined according to the position of the maximum point with respect to a processing portion of the workpiece.

2. The laser machining system of claim 1,

determining the target position using a database of the position of the maximum point set in association with the opening size of the ejection opening and the supply pressure of the assist gas to the nozzle.

3. Laser machining system according to claim 1 or 2,

the laser processing system further has:

and a position acquisition unit that acquires the position of the local maximum point by measurement or calculation.

4. The laser processing system according to any one of claims 1 to 3,

the laser processing system further has:

a moving mechanism that moves the nozzle and the workpiece relative to each other; and

and a movement control unit that controls the movement mechanism to dispose the nozzle at the target position.

5. The laser processing system according to any one of claims 1 to 4,

the target position is determined to be a prescribed range.

6. A method of laser processing a workpiece using the laser processing system of any of claims 1 to 5,

and a jet flow generating unit configured to generate a jet flow of the laser beam, wherein the jet flow is emitted from the emission port of the nozzle in a state where the nozzle is disposed at the target position, and the workpiece is processed by the laser beam.

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